At this early stage in my doctoral program, a specific thesis topic has not yet been selected. However, I have identified a preliminary subject of investigation which I plan to develop into my Pre-Dissertation Project (PDP). Compared to the extensive body of literature regarding the development of consonants in typically developing children, there is relatively little information available regarding the normal process of vowel development. Consequently, there remains a need for longitudinal investigations of vowel development in typically-developing children. For the proposed preliminary investigation, existing data will be used to study vowel development in 10 typically-developing English-speaking children (5 males and 5 females) between the ages of 21 and 33 months. This investigation will involve a spectral analysis of the acoustic properties of vowels including the first two formants (F1, F2) as well as vowel duration. While some developmental studies have investigated vowel overlap in two dimensions, to our knowledge, none have investigated vowel overlap in three-dimensional space. The VOIS (Vowel Overlap Indication Software) analysis program will be used to accomplish this goal. This approach will allow us to gain insight into how monolingual English children use vowel duration in addition to vowel quality to create a phonemic contrast between contrasting vowels. As a long range goal, the methodology and findings gleaned from this initial study will be used to develop dissertation research investigating the development of vowel production in bilingual French/English subjects. [unreadable] [unreadable]